[RideZX6R]

Has anyone posted a list of approx whp limit (ballpark) with each component added to fuel system?

IE... whp limit for...

• Stock LT1 fuel system
• low pressure pump only
• add cam fuel lobe and lash cap only
• add lt4 fuel pump only
• add lt4 injectors only

Obviously we can add combos... but I know if folks could do just the cam lob or just the lash cap for their needs - they'd stop there.

[wnta1ss]

You forgot to mention the low pressure pump. The supply is the basis of your system and if it's not up to the task, then all of the parts you put on the engine are moot.

As far as lash cap, they should only be used to compensate for the lower base circle of an aftermarket camshaft's fuel lobe. If you stick 1 on with a normal cam lobe you are just preloading the hpfp. Guys have broken the high pressure pumps off the engine pulling this stunt.

[RideZX6R]

Originally Posted by wnta1ss

You forgot to mention the low pressure pump. The supply is the basis of your system and if it's not up to the task, then all of the parts you put on the engine are moot.

As far as lash cap, they should only be used to compensate for the lower base circle of an aftermarket camshaft's fuel lobe. If you stick 1 on with a normal cam lobe you are just preloading the hpfp. Guys have broken the high pressure pumps off the engine pulling this stunt.

Edited the list for you... Are you able to answer now?

[DevBlackSS]

Those are a set of tough questions there
Interested to see the answers also

[travislambert]

This doesn't answer all of your questions, but I do have some related experience.

- I made over 600 RWHP and 650 RWTQ on a stock SS fuel low-pressure pump and an LT4 crate engine. The low-pressure pump never even came close to having a problem (logged with HP tuners).

- The stock LT1 high-pressure system taps out at about 600 RWHP. That's why you see the guys with LT1 and an LT4 supercharger underdrive the supercharger a little bit.

- The LT4 high-pressure system is good for at least 700 RWHP.

[mariojmoe]

I am using the lt4 hpfp, 2017 Zl1 lpfp, lt4 injectors, and aftermarket cam to help out as well. I should know where this taps out tomorrow or day after (at a new shop and tuner). I am also running a 2.38 upper and 9.0 lower ud pulley system.

[EDFHOBBIES]

Buddy has a Zl1 his road to modification are as follows... might help w some info..

Zl1 baseline dyno 551 to the wheels stock psi
ZL1 tune, 1 dwn smaller pulley, and headers 580 on 93 and 630 on e77 out of fuel high side
ZL1 Cam added with better fuel lobe 685 8# e77
ZL1 w all above meth 725 13# e77

The low side is requiring a aux pump now... to go further..


this was a race with my friend he was on ZL1 w tune, 1 dwn smaller pulley, e85/e77 when he was stock vs me the Eforce has the advantage.. I doubt it would be close now he can keep up with my TT now.

[ProCharger]

Filled in my .02

• Stock LT1 fuel system
  (580-620rwhp)
  
  
  
  
• low pressure pump only
  (580-650rwhp)
  
  
  
  
• add cam fuel lobe and lash cap only
  (forget the "cap" unless you want headaches, and won't do any good without some sort of LPFP support)
  
  
• add lt4 fuel pump only
  (580-620, won't do you much good with out LPFP support)
  
  
  
• add lt4 injectors only
  (580-620, injectors aren't the issue... would need HPFP and LPFP support)
  

You would need to do a combo like....
Upgraded LPFP (or BAP) and LT4 HPFP
Then you will have full fuel pressure on the low side, and plenty on the highside. Until you run out of LT4 HPFP.....

Then comes your next steps.


But again, as I have stated each car/truck is different.
Some run out of LPFP first, others run out of HPFP first.
Its best to take it to a tuner that knows them inside and out, and purchase parts for what YOUR car needs. (Unless you just wanna throw it all at it, but thats kinda pricy)

[ProCharger]

Originally Posted by travislambert

- The LT4 high-pressure system is good for at least 700 RWHP.

With LT4 injectors, LT4 HPFP, and good intake pump....
I have made 732 rwhp before it ran out. (procharged)

But then a few months later one ran out at 666 rwhp (not kidding on the number, and it was roots blown)
Because it had a HPFP that just wants as good as the last LT4 HPFP.

So I would say the range that I have personally seen in 666rwhp-732rwhp

[RideZX6R]

Originally Posted by ProCharger

Filled in my .02

• Stock LT1 fuel system
  (580-620rwhp)
  
  
  
  
• low pressure pump only
  (580-650rwhp)
  
  
  
  
• add cam fuel lobe and lash cap only
  (forget the "cap" unless you want headaches, and won't do any good without some sort of LPFP support)
  
  
• add lt4 fuel pump only
  (580-620, won't do you much good with out LPFP support)
  
  
  
• add lt4 injectors only
  (580-620, injectors aren't the issue... would need HPFP and LPFP support)
  

You would need to do a combo like....
Upgraded LPFP (or BAP) and LT4 HPFP
Then you will have full fuel pressure on the low side, and plenty on the highside. Until you run out of LT4 HPFP.....

Then comes your next steps.


But again, as I have stated each car/truck is different.
Some run out of LPFP first, others run out of HPFP first.
Its best to take it to a tuner that knows them inside and out, and purchase parts for what YOUR car needs. (Unless you just wanna throw it all at it, but thats kinda pricy)

I really appreciate this info. Would it be safe to assume the above numbers are with pump gas in mind, and E85 would change things?


For my personal car... heads/cam/E85 is probably the name of the game.
However it'll be a little odd, 5.3L Gen5 ported heads and then a specifically matched cam. Ideally the velocity the 5.3L heads will create should make the mid-range more powerful than 6.2L ported heads, but both would make similar power at high RPM. (basically the theory some folks have, myself included is that 6.2L heads might be a bit too big at lower rpms for anything other the FI applications, which I will not have - but realize this forum is the place to ask fueling questions).

[travislambert]

Originally Posted by ProCharger

With LT4 injectors, LT4 HPFP, and good intake pump....
I have made 732 rwhp before it ran out. (procharged)

But then a few months later one ran out at 666 rwhp (not kidding on the number, and it was roots blown)
Because it had a HPFP that just wants as good as the last LT4 HPFP.

So I would say the range that I have personally seen in 666rwhp-732rwhp

Good to know. Thank You!

[ProCharger]

Originally Posted by RideZX6R

I really appreciate this info. Would it be safe to assume the above numbers are with pump gas in mind, and E85 would change things?

E85 adds the stress of having to move more volume.
So take 15-30% off the numbers I posted, depending on the content % you run

[jessrayo]

This is what I saw on my car. It has a twin turbo system so it will have slight differences than the superchargers.

• Stock LT1 fuel system - 566whp (91 octane)
• low pressure pump only - 653whp (91 octane)
• add lt4 fuel pump only - In a detailed engineering report on direct injection from GM they specifically stated that their DI fuel injectors are designed to best atomize the fuel at specific pressures related to the corresponding GM mechanical fuel pump so they did not recommend swapping the lt4 pump or injectors individually but rather treat them as a combined unit. GM and other tuners have noted that at the extreme upper limits the injectors may not fully atomize the fuel and it may begin to "wash" the cylinder giving false air/fuel readings. I swapped both together and went to 758whp using 110 octane. The high compression lt1 engine was not allowing much improvement with this "extra lt4 fuel and boost capacity" on pump gas due to increased knock with the corresponding increased boost. Had to go to race gas to use the lt4 mechanical fuel pump potential.

I currently keep my car tuned to 650ish and run pump 91. There is a lot more potential running e85 because of its resistance to knock but it is not readily available in my area of the country.

I feel if you want to go much above 650 you really need to change the pistons and if I was swapping pistons I would reduce the compression ratio to allow more usable boost at pump gas octane levels.

[PRAY]

Good read. Anyone care to comment on where they think a ZL1 in tank and 32% fuel lobe will be maxed out at with the stock LT1 injectors and High side pump?